Micropump and driving method thereof

ABSTRACT

Provided are a micropump that makes it possible to reduce the entire size and improve pumping performance of fluid, and a method of operating the micropump. The micropump includes a case that forms a first space and a second space that are connected through a connection channel, a fluid intake pipe that is connected to the first space, a fluid discharge pipe that is connected to the second space, a first deforming member that is disposed on the case to cover the first space, and a second deforming member that is disposed on the case to cover the second space. The second deforming member is formed larger than the first deforming member and the maximum displacement of the second deforming member is larger than the maximum displacement of the first deforming member.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean PatentApplication No. 10-2010-0082546 filed in the Korean IntellectualProperty Office on Aug. 25, 2010, the entire contents of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a micropump for delivering fluid. Moreparticularly, the present invention relates to a micropump that sucksfluid by generating a strong suction force in a channel and delivers thesucked fluid to the downstream, and a driving method thereof.

(b) Description of the Related Art

With the development in the micromachining technology, researches onmicrodevices, such as MEMS (Micro-Electro Mechanical System), have beenactively conducted. In the devices, a micropump, a device thatmanipulates a very small amount of fluid, using fluid mechanics, isapplied to various fields, including medical chemistry systems andmedical equipment, such as chemical analyzing systems and medicinedelivery systems, and inkjet heads.

The micropump may be implemented by a piezoelectric micropump using apiezoelectric actuator. A typical piezoelectric micropump has aconfiguration in which three or more piezoelectric actuators aredisposed in parallel in one pump case and electrically connected to acontrol device.

According to the piezoelectric micropump, when an electromotive force isapplied to the piezoelectric actuators from the control device, thepiezoelectric actuators sequentially operate and make a pumping actionthat sucks and discharges fluid. The micropump equipped with a pluralityof piezoelectric actuators, as described above, can easily control theflow of fluid, but has a defect in that the pumping performance is lowand the size is large.

The above information disclosed in this Background section is only forenhancement of understanding of the background of the invention andtherefore it may contain information that does not form the prior artthat is already known in this country to a person of ordinary skill inthe art.

SUMMARY OF THE INVENTION

The present invention has been made in an effort to provide a micropumpthat can improve pumping performance while decreasing the entire size,and a driving method thereof.

An exemplary embodiment of the present invention provides a micropumpincluding: a case that forms a first space and a second space that areconnected through a connection channel; a fluid intake pipe that ispositioned at a side of the case and connected to the first space; afluid discharge pipe that is positioned at the other side of the caseand connected to the second space; a first deforming member that isdisposed on the case to cover the first space and deforms in response toan electric signal; and a second deforming member that is disposed onthe case to cover the second space and deforms in response to anelectric signal. The second deforming member is formed larger than thefirst deforming member and the maximum displacement of the seconddeforming member is larger than the maximum displacement of the firstdeforming member.

The first deforming member and the second deforming member may beimplemented by piezoelectric actuators. The first deforming plate mayinclude a first conductive elastic plate and a first piezoelectricdevice and the second deforming member may include a second conductiveelastic plate and a second piezoelectric device.

The micropump may further include: a plurality of lead wires that isconnected to the first conductive elastic plate, the first piezoelectricdevice, the second conductive elastic plate, and the secondpiezoelectric device, respectively; and a controller that iselectrically connected with the plurality of lead wires.

On the other hand, the first deforming member and the second deformingmember may be made of artificial muscles. The first deforming member mayinclude a first imitative muscle and a first electrode and the seconddeforming member may include a second imitative muscle and a secondelectrode.

The first imitative muscle and the second imitative muscle may includenanofiber made of electric active hydrogel. The micropump may include: apair of lead wires that is connected to the first electrode and thesecond electrode, respectively; and a controller that is electricallyconnected with the pair of lead wires.

The volume of the second space may be larger than the volume of thefirst space.

The micropump may further include: an on/off valve that is disposed inthe connection channel; and an anti-backflow member that is disposed inthe fluid intake pipe and the fluid discharge pipe. On the other hand,the micropump may further include an anti-backflow member disposed inthe fluid intake pipe, the connection channel, and the fluid dischargepipe.

The on/off valve may be a piezoelectric valve that includes a firstpiezoelectric disk and a second piezoelectric disk that are disposed inparallel with the connection channel.

The anti-backflow member may be formed in a cone shape of which theinner diameter gradually increases from a side facing the fluid intakepipe to the opposite side facing the fluid discharge pipe.

On the other hand, the anti-backflow member may include: a deformingplate that is formed of a thin layer and has a fixed end and a free end;and a fixing protrusion that is positioned ahead of the free end of thedeforming plate in a forward direction toward the fluid discharge pipefrom the fluid intake pipe.

Another exemplary embodiment of the present invention provides a methodof operating a micropump, including: a first section where the firstdeforming member expands from the minimum displacement to the maximumdisplacement and the second deforming member initially expands from theminimum displacement; a second section where the first deforming memberretracts from the maximum displacement and the second deforming memberexpands to the maximum displacement; and a third section where the firstdeforming member retracts to the minimum displacement and the seconddeforming member retracts from the maximum displacement.

The second deforming member may start to expand from the minimumdisplacement with a time difference from the maximum displacementposition of the first deforming member in the first section. The minimumdisplacement position of the first deforming member may have a timedifference from the maximum displacement position of the seconddeforming member in the third section.

Yet another exemplary embodiment of the present invention provides amethod of operating a micropump, including: a first section where thefirst deforming member expands from the minimum displacement to themaximum displacement and the second deforming member initially expandsfrom the minimum displacement; a second section where the firstdeforming member retracts from the maximum displacement to the minimumdisplacement and the second deforming member expands to the maximumdisplacement; and a third section where the first deforming memberinitially expands from the minimum displacement and the second deformingmember retracts to the minimum displacement.

The second deforming member may start to expand from the minimumdisplacement with a time difference from the maximum displacementposition of the first deforming member in the first section. The minimumdisplacement position of the first deforming member may agree with themaximum displacement position of the second deforming member in thesecond section.

Still another exemplary embodiment of the present invention a method ofoperating a micropump, including: a first section where fluid is suckedinto the first space by expanding the first deforming member from theminimum displacement to the maximum displacement; a second section wherefluid is sucked into the first space and the second space by retractingthe first deforming member from the maximum displacement to the minimumdisplacement and expanding the second deforming member from the minimumdisplacement to the maximum displacement; and a third section where thefluid in the first space and the second space is discharged byretracting the second deforming member from the maximum displacement tothe minimum displacement.

The maximum displacement position of the first deforming member mayagree with the minimum displacement position of the second deformingmember.

In all of the methods of operating a micropump, the on/off valve may bepositioned in the connection channel of the micropump and the on/offvalve may open the connection channel by operating simultaneously withthe expansion of the second deforming member and may close theconnection channel by operation simultaneously with that the seconddeforming member reaches the maximum displacement.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of a micropump according to a first exemplaryembodiment of the present invention.

FIG. 2 is a cross-sectional view of the micropump according to the firstexemplary embodiment of the present invention.

FIG. 3 is a schematic diagram showing an on/off valve in the micropumpshown in FIG. 1.

FIG. 4 is a schematic diagram showing an exemplary variation of ananti-backflow member in the micropump shown in FIG. 1.

FIG. 5 is a cross-sectional view of a micropump according to a secondexemplary embodiment of the present invention.

FIG. 6 is a cross-sectional view of a micropump according to a thirdexemplary embodiment of the present invention.

FIG. 7 is a cross-sectional view of a micropump according to a fourthexemplary embodiment of the present invention.

FIG. 8 is a waveform diagram showing applied signals of a firstdeforming member and a second deforming member shown to illustrate afirst operation method of a micropump.

FIG. 9 is a waveform diagram showing applied signals of a firstdeforming member and a second deforming member shown to illustrate asecond operation method of a micropump.

FIG. 10 is a waveform diagram showing applied signals of a firstdeforming member and a second deforming member shown to illustrate athird operation method of a micropump.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present invention will be described more fully hereinafter withreference to the accompanying drawings, in which exemplary embodimentsof the invention are shown. As those skilled in the art would realize,the described embodiments may be modified in various different ways, allwithout departing from the spirit or scope of the present invention.

FIG. 1 and FIG. 2 are a plan view and a cross-sectional view of amicropump according to a first exemplary embodiment of the presentinvention.

Referring to FIG. 1 and FIG. 2, a micropump 100 according to the firstexemplary embodiment includes a case 10, a fluid intake pipe 12, a fluiddischarge pipe 14, a first deforming member 16, a second deformingmember 18 and a controller 20.

The case 10 has a first space 101, a connection channel 103, and asecond space 102, sequentially formed in one direction therein. Thefirst space 101 and the second space 102 are separately positioned at apredetermined distance from each other and the connection channel 103smaller in size than the two spaces 101 and 102 is formed between thetwo spaces 102 and 103 and connects the two spaces 101 and 102.

The fluid intake pipe 12 is fixed to a side of the case 10 that is incontact with the first space 101 and connected with the first space 101.The fluid discharge pipe 14 is fixed to the other side of the case 10that is in contact with the second space 102 and connected with thesecond space 102. FIG. 1 and FIG. 2 show when the fluid intake pipe 12is positioned at the left of the case 10 and the fluid discharge pipe 14is positioned at the right of the case 10, as an example.

The first deforming member 16 is disposed on the case 10 to cover thefirst space 101 and the second deforming member 102 is disposed on thecase 10 to cover the second space 102. The first deforming member 16 andthe second deforming member 18 are positioned at a predetermineddistance from each other. In the exemplary embodiment, the firstdeforming member 16 and the second deforming member 18 are implementedby piezoelectric actuators.

The first deforming member 16 has a stacking structure composed of afirst conductive elastic plate 161 and a first piezoelectric element 162while the second deforming member 18 has a stacking structure composedof a second conductive elastic plate 181 and a second piezoelectricelement 182. A lead wire 22 is connected to the first conductive elasticplate 161, the first piezoelectric element 162, the second conductiveelastic plate 181, and the second piezoelectric element 182,respectively, and the lead wires 22 are connected to the controller 20.

The first deforming member 16 and the second deforming member 18 make anexpanding or retracting displacement in accordance with the polaritywhen an electromotive force is applied from the controller 20. Themaximum displacement (second displacement) of the second deformingmember 18 close to the fluid discharge pipe 14 is larger than themaximum displacement (first displacement) of the first deforming member16 close to the fluid intake pipe 12. As a result, the second deformingmember 18 generates a pressure inclination larger than the firstdeforming member 16, such that it is possible to effectively control theflow of fluid in the operation process of the micropump 100, which isdescribed below.

The second deforming member 18 is formed larger than the first deformingmember 16 to increase the maximum displacement of the second deformingmember 18. That is, the second conductive elastic plate 181 is formedlarger than the first conductive elastic plate 161 and the secondpiezoelectric device 182 is formed larger than the first piezoelectricdevice 162. Further, the volume of the second space 102 that is incontact with the second deforming member 18 is defined larger than thevolume of the first space 101 that is in contact with the firstdeforming member 16.

Further, the micropump 100 includes an on/off valve 24 disposed in theconnection channel 103 and an anti-backflow member 26 disposed in thefluid discharge pipe 14. The anti-backflow member 26 may also bedisposed in the fluid intake pipe 12. The on/off valve 24 is an activevalve and opens or closes the connection channel 103 while the operationis controlled by the controller 20. The on/off valve 24 may beimplemented by a common mechanical valve or a piezoelectric valve usinga piezoelectric device.

FIG. 3 is a schematic diagram showing an on/off valve in the mircropumpshown in FIG. 1.

Referring to FIG. 3, the piezoelectric valve 240 includes a firstpiezoelectric disk 241 and a second piezoelectric disk 242 that aredisposed in parallel with the connection channel 103. The firstpiezoelectric disk 241 may have a stacking structure of a conductiveelastic plate and a piezoelectric device and the second piezoelectricdisk 242 may also have a stacking structure of a conductive elasticplate and a piezoelectric device. The first piezoelectric disk 241 andthe second piezoelectric disk 242 are connected with the controller 20through the lead wires 243, respectively.

The first piezoelectric disk 242 and the second piezoelectric disk 242close the connection channel 103 by coming in contact with each otherwhen an electromotive force is not applied from the controller 20, andopens the connection channel 103 by expanding away from each other whenan electromotive force is applied from the controller 20. Thepiezoelectric valve 240 can open/close the connection channel 103 fastby these operations.

As shown in FIG. 3, the piezoelectric valve 240 is shown to described anexample of the on/off valve 24, and the on/off valve 24 of the presentinvention is not limited to the piezoelectric valve 240 and all valvesthat can open/close the connection channel 103 can be used.

Referring to FIG. 1 and FIG. 2, the anti-backflow member 26 is a passivevalve, which allows the fluid to smoothly flow in the forward directiontoward the fluid discharge pipe 14 from the fluid intake pipe 12, whilepreventing the fluid from flowing in the opposite direction.

The anti-backflow member 26 may be formed in a cone shape of which theinner diameter gradually increases from a side facing the fluid intakepipe 12 to the opposite side facing the fluid discharge pipe 14. In thiscase, the fluid cannot pass through the anti-backflow member 26 bypressure that increases when flowing in the backward direction, suchthat the anti-backflow member 26 can effectively stop the backward flowof the fluid.

FIG. 4 is a schematic diagram showing an exemplary variation of ananti-backflow member in the micropump shown in FIG. 1.

Referring to FIG. 4, the anti-backflow member 260 may have a structurecomposed of a deforming plate 28 and a fixing protrusion 30, instead ofthe cone shape. The deforming plate 28 may be made of a thin layer thatcan easily deform. The deforming plate 28 has a fixed end 281 that ispartially fixed in the fluid intake pipe 12 and the fluid discharge pipe14 and a free end 282 that is separated, not fixed, at the otherportion. Further, the fixing protrusion 30 is positioned ahead of thefree end 282 of the deforming plate 28 in the forward direction towardthe fluid discharge pipe 14 from the fluid intake pipe 12.

Accordingly, the anti-backflow member 260 opens the channel while thefree end 282 of the deforming plate 28 moves away from the fixingprotrusion 30 when the fluid flows in the forward direction, whereas itcloses the channel while the free end 282 of the deforming plate 28 isblocked by the fixing protrusion 30 when the fluid flows in the backwarddirection. As a result, the anti-backflow member 260 can effectivelystop the backward flow of the fluid.

Referring to FIG. 1 and FIG. 2, the micropump 100 according to the firstexemplary embodiment can effectively control the fluid flow even beingequipped with the two deforming members 16 and 18 by setting the maximumdisplacement of the second deforming member 18 larger than the maximumdisplacement of the first deforming member 16. Therefore, it is possibleto reduce the size of the micropump 100 by decreasing the number ofdeforming members 16 and 18.

Further, the micropump 100 according to the first exemplary embodimentcan pump fast the viscous fluid in the forward direction by using theon/off valve 24 and the anti-backflow member 26, in addition to thefirst and second deforming members 16 and 18, such that pumpingperformance can be improved.

FIG. 5 is a cross-sectional view of a micropump according to a secondexemplary embodiment of the present invention.

Referring to FIG. 5, a micropump 200 according to the second exemplaryembodiment has the same configuration as the micropump 100 of the firstexemplary embodiment, except that the anti-backflow member 26 isdisposed in the connection channel 103. The same members as those in thefirst exemplary embodiment are indicated by the same reference numerals.

The micropump 200 according to the second exemplary embodiment is notprovided with an on/off valve, and an anti-backflow member 26 isdisposed in a connection channel 103 and a fluid discharge pipe 14. Theanti-backflow member 26 may also be disposed in a fluid intake pipe 12.

The anti-backflow member 26 may be formed in a cone shape of which theinner diameter gradually increases from a side facing the fluid intakepipe 12 to the opposite side facing the fluid discharge pipe 14. On theother hand, as shown in FIG. 4, the anti-backflow member 260 may have astructure composed of a deforming plate 28 and a fixing protrusion 30.

FIG. 6 is a cross-sectional view of a micropump according to a thirdexemplary embodiment of the present invention.

Referring to FIG. 6, a micropump 300 according to the third exemplaryembodiment has the same configuration as the micropump 100 according tothe first exemplary embodiment, except that a first deforming member 160and a second deforming member 180 are made of artificial muscles. Thesame members as those in the first exemplary embodiment are indicated bythe same reference numerals.

The first deforming member 160 is composed of a first imitative muscle163 and a first electrode 164 and the first electrode 164 iselectrically connected with a controller 20 through the correspondinglead wire 22. The second deforming member 180 is composed of a secondimitative muscle 183 and a second electrode 184 and the second electrode184 is electrically connected with a controller 20 through thecorresponding lead wire 22. The second imitative muscle 183 is formedlarger than the first imitative muscle 163 such that the maximumdisplacement of the second deforming member 180 is larger than themaximum displacement of the first deforming member 160.

The first and the second imitative muscles 163 and 183 may be made ofnanofiber that can react to electric stimulation, and are physicallyretracted or expanded by electric stimulation received through the firstand the second electrodes 164 and 184. The first and the secondimitative muscles 163 and 183 may be manufactured by composing nanofiberwith electric active hydrogel. The material and manufacturing method ofthe first and the second imitative muscles 163 and 183 are not limitedto the exemplary embodiment and may be variously changed.

FIG. 7 is a cross-sectional view of a micropump according to a fourthexemplary embodiment of the present invention.

Referring to FIG. 7, a micropump 400 according to the fourth exemplaryembodiment has the same configuration as the micropump 200 according tothe second exemplary embodiment, except that the first deforming member160 and the second deforming member 180 are made of artificial muscles.The same members as those in the second exemplary embodiment areindicated by the same reference numerals. The configurations of thefirst deforming member 160 and the second deforming member 180 are thesame as those in the third exemplary embodiment, such that the detaileddescription is not provided.

FIG. 8 is a waveform diagram showing applied signals of a firstdeforming member and a second deforming member shown to illustrate afirst operation method of the micropumps according to the first tofourth exemplary embodiments. One cycle waveform is shown in (a) of FIG.8 and a continuous waveform is shown in (b) of FIG. 8. In (a) of FIG. 8,the vertical axis shows the displacement of the first deforming memberand the second deforming member, which shows the amount of maximumupward displacement, assuming that the flat state is 0.

Referring to FIG. 8, the operation method of the micropump includes afirst section, a second section, and a third section. The first sectionis a section where an electric signal is applied to the first deformingmember such that the first deforming member expands to the maximumdisplacement (first displacement) while an electric signal is applied tothe second deforming member, with a time difference from the firstdeforming member, such that the second deforming member initiallyexpands. The second section is a section where the first deformingmember retracts from the maximum displacement while the second deformingmember expands to the maximum displacement (second displacement). Thethird section is a section where the first deforming member retracts tothe minimum displacement while the second deforming member retracts.

Referring to FIG. 2 and FIG. 8, the first deforming member 16 expandsfrom the minimum displacement to the maximum displacement in the firstsection. Therefore, an intake force is generated in the first space 101and the fluid is sucked from the first intake pipe 12 into the firstspace 101. In the exemplary embodiment, the minimum displacement implieszero displacement.

In the first section, the second deforming member 18 starts to expandfrom the minimum displacement with a time difference “a” shown in FIG.8, before the first deforming member 16 reaches the maximumdisplacement. Accordingly, the fluid in the first space 101 can besucked into the second space 102 when the fluid in the first space 101keeps the inertia in the forward direction, by opening the second space102, such that energy efficiency of the micropump 100 can be increased.

In the second section, the first deforming member 16 starts to retractsfrom the maximum displacement and the second deforming member 18 expandsto the maximum displacement. Accordingly, the maximum intake force isgenerated in the second space 102, such that the fluid is sucked intothe second space 102 through the first space 101 and the connectionchannel 103. Since the maximum displacement of the second deformingmember 18 is larger than the maximum displacement of the first deformingmember 16, the second deforming member 18 makes a pressure inclinationlarger than the first deforming member 16.

In the third section, the first deforming member 16 retracts to theminimum displacement and the second deforming member 18 also retracts.The minimum displacement of the second deforming member 18 may exists inthe first section of the next cycle. As the first deforming member 16and the second deforming member 18 retract, the fluid in the first space101 and the second space 102 is discharged to the fluid discharge pipe14. The first deforming member 16 has a function of preventing backwarddischarge through the fluid intake pipe 12, when the first deformingmember 16 keeps the minimum displacement in the third section.

When the on/off valve 24 is disposed in the connection channel 103, theon/off valve 24 opens the connection channel 103 by operatingsimultaneously with the expansion of the second deforming member 18 inthe first section. Further, the on/off valve 24 closes the connectionchannel 103 by operating simultaneously with that the second deformingmember 18 reaches the maximum displacement between the second sectionand the third section.

The on/off valve 24 actively controls the time when the fluid flows intothe second space 102 from the first space 101. In particular, when theon/off valve 24 is implemented by the piezoelectric valve 240, as shownin FIG. 3, the piezoelectric valve 240 has a structure than can expandby itself, such that the piezoelectric valve 240 can contribute toincreasing the pumping performance and the energy efficiency of themicropump 100 by generating an intake force by itself.

Further, the anti-backflow member 26 disposed in the fluid intake pipe12 and the fluid discharge pipe 14 prevents backward flow of the fluidin the operation of the micropump 100.

As described above, the first, second, and third sections constitute onepumping cycle while the second deforming member 18 makes a displacementlarger than the first deforming member 16 and accordingly makes apressure inclination larger than the first deforming member 16.Therefore, the micropump 100 according to the present exemplaryembodiment can effectively send the fluid in the forward direction fromthe fluid intake pipe 12 to the fluid discharge pipe 14 by increasingthe pumping performance, and it is possible to reduce the entire size bydecreasing the number of deforming members 16 and 18.

In the operation method of the micropump shown in FIG. 8, the maximumdisplacement position of the second deforming member 18 and the minimumdisplacement position of the first deforming member 16 do not agree witheach other. That is, the second deforming member 18 expands to themaximum displacement and then the first deforming member 16 retracts tothe minimum displacement. Further, a time difference as much as thesecond section is maintained between the maximum displacement positionof the first deforming member 16 and the maximum displacement positionof the second deforming member 18.

FIG. 9 is a waveform diagram showing applied signals of a firstdeforming member and a second deforming member shown to illustrate asecond operation method of the micropumps according to the firstexemplary embodiment to the fourth exemplary embodiment. One cyclewaveform is shown in (a) of FIG. 9 and a continuous waveform is shown in(b) of FIG. 9.

Referring to FIG. 9, the operation method of the micropump includes afirst section, a second section, and a third section. The first sectionis a section where an electric signal is applied to the first deformingmember such that the first deforming member expands to the maximumdisplacement (first displacement) while an electric signal is applied tothe second deforming member, with a time difference from the firstdeforming member, such that the second deforming member initiallyexpands. The second section is a section where the first deformingmember retracts from the maximum displacement to the minimumdisplacement while the second deforming member expands to the maximumdisplacement (second displacement). The third section is a section wherethe first deforming member initially expands from the minimumdisplacement while the second deforming member retracts to the minimumdisplacement.

The second operation method of the micropump includes the same processesas those in the first operation method, except that the minimumdisplacement position of the first deforming member agrees with themaximum displacement position of the second deforming member and thefirst deforming member initially expands in the third section.

As described above, as the minimum displacement position of the firstdeforming member agrees with the maximum displacement position of thesecond deforming member, the first deforming member completely functionsas a valve when the second deforming member retracts in the thirdsection, such that it is possible to prevent the backward flow of thefluid and increase the pumping performance. Further, according to thesecond operation method, the flow rate from the first deforming memberto the second deforming member is larger than that in the firstoperation method, such that it is possible to increase the availableflow rate of the micropump without increasing the size of the micropump.

FIG. 10 is a waveform diagram showing applied signals of a firstdeforming member and a second deforming member shown to illustrate athird operation method of the micropumps according to the firstexemplary embodiment to the fourth exemplary embodiment. One cyclewaveform is shown in (a) of FIG. 10 and a continuous waveform is shownin (b) of FIG. 10.

Referring to FIG. 10, the operation method of the micropump includes afirst section, a second section, and a third section. The first sectionis a section where an electric signal is applied to the first deformingmember such that the first deforming member expands to the maximumdisplacement (first displacement). The second section is a section wherethe first deforming member retracts from the maximum displacement to theminimum displacement while an electric signal is applied to the seconddeforming member such that the second deforming member expands to themaximum displacement (second displacement). The third section is asection where the first deforming member is maintained at the minimumdisplacement while the second deformation member retracts to the minimumdisplacement.

The third operation method of the micropump includes the same processesas those in the second operation method except that the maximumdisplacement position of the first deforming member agrees with theminimum displacement position of the second deforming member.

While this invention has been described in connection with what ispresently considered to be practical exemplary embodiments, it is to beunderstood that the invention is not limited to the disclosedembodiments, but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

What is claimed is:
 1. A micropump comprising: a case that forms a firstspace and a second space that are connected through a connectionchannel; a fluid intake pipe that is positioned at a side of the caseand connected with the first space; a fluid discharge pipe that ispositioned at the other side of the case and connected with the secondspace; a first deforming member that is disposed on the case to coverthe first space and deformed by an electric signal; and a seconddeforming member that is disposed on the case to cover the second spaceand deformed by an electric signal, wherein the second deforming memberis formed larger than the first deforming member, and the maximumdisplacement of the second deforming member is larger than the maximumdisplacement of the first deforming member.
 2. The micrcopump of claim1, wherein: the first deforming member and the second deforming memberare implemented by piezoelectric actuators.
 3. The micropump of claim 2,wherein: the first deforming plate includes a first conductive elasticplate and a first piezoelectric device, and the second deforming memberincludes a second conductive elastic plate and a second piezoelectricdevice.
 4. The micropump of claim 3, further comprising: a plurality oflead wires that is connected to the first conductive elastic plate, thefirst piezoelectric device, the second conductive elastic plate, and thesecond piezoelectric device, respectively; and a controller that iselectrically connected with the plurality of lead wires.
 5. Themicropump of claim 1, wherein: the first deforming member and the seconddeforming member are made of artificial muscles.
 6. The micropump ofclaim 5, wherein: the first deforming member includes a first imitativemuscle and a first electrode, and the second deforming member includes asecond imitative muscle and a second electrode.
 7. The micropump ofclaim 6, wherein: the first imitative muscle and the second imitativemuscle include nanofiber made of electric active hydrogel.
 8. Themicropump of claim 6, further comprising: a pair of lead wires that isconnected to the first electrode and the second electrode, respectively;and a controller that is electrically connected with the pair of leadwires.
 9. The micropump of claim 1, wherein: the volume of the secondspace is larger than the volume of the first space.
 10. The micropump ofclaim 1, further comprising: an on/off valve that is disposed in theconnection channel; and an anti-backflow member that is disposed in thefluid intake pipe and the fluid discharge pipe.
 11. The micropump ofclaim 10, wherein: the on/off valve is a piezoelectric valve thatincludes a first piezoelectric disk and a second piezoelectric disk thatare disposed in parallel with the connection channel.
 12. The micropumpof claim 10, wherein: the anti-backflow member is formed in a cone shapeof which the inner diameter gradually increases from a side facing thefluid intake pipe to the opposite side facing the fluid discharge pipe.13. The micropump of claim 10, wherein: the anti-backflow memberincludes: a deforming plate that is formed of a thin layer and has afixed end and a free end; and a fixing protrusion that is positionedahead of the free end of the deforming plate in a forward directiontoward the fluid discharge pipe from the fluid intake pipe.
 14. Themicropump of claim 1, further comprising: an anti-backflow member thatis disposed in the fluid intake pipe, the connection channel, and thefluid discharge pipe.
 15. The micropump of claim 14, wherein: theanti-backflow member is formed in a cone shape of which the innerdiameter gradually increases from a side facing the fluid intake pipe tothe opposite side facing the fluid discharge pipe.
 16. The micropump ofclaim 14, wherein: the anti-backflow member includes: a deforming platethat is formed of a thin layer and has a fixed end and a free end; and afixing protrusion that is positioned ahead of the free end of thedeforming plate in a forward direction toward the fluid discharge pipefrom the fluid intake pipe.
 17. A method of operating the micropump ofclaim 1, comprising: a first section where the first deforming memberexpands from the minimum displacement to the maximum displacement andthe second deforming member initially expands from the minimumdisplacement; a second section where the first deforming member retractsfrom the maximum displacement and the second deforming member expands tothe maximum displacement; and a third section where the first deformingmember retracts to the minimum displacement and the second deformingmember retracts from the maximum displacement.
 18. The method of claim17, wherein: the second deforming member starts to expand from theminimum displacement with a time difference from the maximumdisplacement position of the first deforming member in the firstsection.
 19. The method of claim 17, wherein: the minimum displacementposition of the first deforming member has a time difference from themaximum displacement position of the second deforming member in thethird section.
 20. The method of claim 17, wherein: an on/off valve isdisposed in a connection channel of the micropump, and the on/off valveopens the connection channel by operating simultaneously with theexpansion of the second deforming member and closes the connectionchannel by operating simultaneously with that the second deformingmember reaches the maximum displacement.
 21. A method of operating themicropump of claim 1, comprising: a first section where the firstdeforming member expands from the minimum displacement to the maximumdisplacement and the second deforming member initially expands from theminimum displacement; a second section where the first deforming memberretracts from the maximum displacement to the minimum displacement andthe second deforming member expands to the maximum displacement; and athird section where the first deforming member initially expands fromthe minimum displacement and the second deforming member retracts to theminimum displacement.
 22. The method of claim 21, wherein: the seconddeforming member starts to expand from the minimum displacement with atime difference from the maximum displacement position of the firstdeforming member in the first section.
 23. The method of claim 21,wherein: the maximum displacement position of the first deforming memberagrees with the maximum displacement position of the second deformingmember in the second section.
 24. The method of claim 21, wherein: anon/off valve is disposed in a connection channel of the micropump, andthe on/off valve opens the connection channel by operatingsimultaneously with the expansion of the second deforming member andcloses the connection channel by operating simultaneously with that thesecond deforming member reaches the maximum displacement.
 25. A methodof operating the micropump of claim 1, comprising: a first section wherefluid is sucked into the first space by expanding the first deformingmember from the minimum displacement to the maximum displacement; asecond section where fluid is sucked into the first space and the secondspace by retracting the first deforming member from the maximumdisplacement to the minimum displacement and expanding the seconddeforming member from the minimum displacement to the maximumdisplacement; and a third section where the fluid in the first space andthe second space is discharged by retracting the second deforming memberfrom the maximum displacement to the minimum displacement.
 26. Themethod of claim 25, wherein: the maximum displacement position of thefirst deforming member agrees with the minimum displacement position ofthe second deforming member.
 27. The method of claim 25, wherein: anon/off valve is disposed in a connection channel of the micropump, andthe on/off valve opens the connection channel by operatingsimultaneously with the expansion of the second deforming member andcloses the connection channel by operating simultaneously with that thesecond deforming member reaches the maximum displacement.